Some years ago, sound reproduction equipment went through a revolution and hi-fidelity and stereo sound equipment became available for use in homes and other places where only a relatively small size listening room was available. The electronics of such equipment has progressed now to such a point that the component of most stereo systems that limits the realism of the system is the loudspeaker system. This is because it has been very difficult to mechanically move air in a small room to reproduce the acoustic effects of the original material which were usually created in a large music hall or a studio especially treated to reduce wall reflections. In most homes, hi-fidelity equipment is placed in small rooms with very reflective walls and at levels where psycho-acoustics begin to take effect. Standing waves form in the room to produce interference in the form of variable increases in pressure at different areas of the room as the frequency range of the reproduced sound changes. These interference effects are likely to be very bad in the prime listening area between the two speaker enclosures of a stereo type hi-fidelity system and are extremely distracting at normal listening levels of 90 dba. To the listener the interference effects make it appear that some frequencies are continuously dropping out. This causes listener fatigue which is the prime reason that most people dislike "loud music" when reproduced by a stereo hi-fidelity system. Even people who have owned conventional stereo equipment for years must limit the period of time that they can listen to recorded multiple frequency sounds at normal listening levels.
The fatigue inducing effects can be greatly reduced by listening in an anechoic chamber or very dead environment where there are no reflections and hence very small interference effects. Except for the very wealthy, such rooms are out of the question and therefore there has been a need to produce a speaker system with a smooth response that has no peaks or resonances in the overall output and which can accommodate a small reflective room. Being frustrated with conventional speaker systems, others have tried to find a way to correct rooms electronically. Unfortunately, this approach results in complicated losses in the signal path reducing the accuracy of the program before it reaches the speakers. The present critical alignment loudspeaker systems do not react drastically with a room and present a working alternative to solve the room-sound interaction problem.